raw material: 55SiMnMo production process : involving steel rolling, forging, normalizing, quenching and tempering, etc Shank size: H22 108mm/H25 108mm Taper degree: 7, 11 we offer four quality products including Grade A drill rod Qs and GTIII can be applied to solid rocks Grade B drill rod QSAA and G30 is suitable for IV level or above and 12 rocks, Grade C and Grade D dril rod suitable for IV level or below and f 8 rocks.